The laser printer and other image-forming devices described in Japanese Patent Application Publication No-2007-199675 are well known in the art. This type of image-forming device includes a casing accommodating an endless belt for conveying paper or another recording medium, and an image-forming unit for forming images on the recording medium.
In such a device, paper dust generated from the paper, toner generated from the image-forming unit, and other extraneous matter is often deposited on the outer surface of the belt. One technique for removing this extraneous matter from the belt is as follows. First, a single cleaning roller is disposed in contact with the outer surface of the belt and is urged against the belt with pressure. In addition, a single backup roller is disposed on the inside surface of the belt at a position opposing the cleaning roller through the belt. By urging the backup roller toward the cleaning roller, the force with which the cleaning roller contacts the belt can be increased.
With this construction, the extraneous matter is transferred onto the cleaning roller by driving the cleaning roller to rotate. The matter transferred to the cleaning roller is subsequently transferred to a metal roller in contact with the cleaning roller and then scraped off the metal roller by a blade that contacts the metal roller with pressure.